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991.
Understanding the atomic and electronic origin of mechanical property in thaumasite and ettringite mineral crystals
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Saro San Neng Li Yong Tao Wenqin Zhang Wai‐Yim Ching 《Journal of the American Ceramic Society》2018,101(11):5177-5187
Ettringite and thaumasite are 2 of the relevant secondary products in portland cement minerals. They are rare crystals with high water content. Two density functional theory based ab initio packages VASP and the OLCAO were used for exploring the geometry structure, electronic, and mechanical properties of ettringite and thaumasite. The calculations focus on the comparison of their structures and properties to gain insights that can reveal the minute difference in properties due to differences in their structure, composition and water content. Detailed analysis of interatomic bonding shows the similarities and subtle difference between them even though thaumasite has the Si tetrahedron as the backbone unit in contrast to ettringite with Al‐columns and no Si atoms. Moreover, thaumasite has strong C–O bonds that are absent in ettringite, and ettringite has far more water molecules with a substantial contribution from the hydrogen bonding. It is shown that the role played by relatively strong S–O bonds in both crystals has a large impact on the hydration in these crystals. On the basis of calculated total bond order density, it is concluded that thaumasite is slightly more cohesive than ettringite consistent with the calculated mechanical properties. The detailed comparative results for these 2 important minerals we obtained in this paper, many of them for the first time, will pave the way to understanding the structure and electronic structure origin of other more complex cement crystals. 相似文献
992.
PtCoFe Nanowire Cathodes Boost Short‐Circuit Currents of Ru(II)‐Based Dye‐Sensitized Solar Cells to a Power Conversion Efficiency of 12.29%
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Chin‐Cheng Chiang Chang‐Yu Hung Shang‐Wei Chou Jing‐Jong Shyue Kum‐Yi Cheng Pei‐Jen Chang Ya‐Yun Yang Ching‐Yen Lin Ting‐Kuang Chang Yun Chi Hung‐Lung Chou Pi‐Tai Chou 《Advanced functional materials》2018,28(3)
PtCoFe nanowires with different alloying compositions are chemically prepared and acted as counter electrodes (CEs) in dye‐sensitized solar cells (DSSCs) with Ru(II)‐based dyes. Due to their superior reduction activity, PtCoFe nanowires with rich (111) facets enhance the performance of DSSCs. Hence, N719 DSSCs with PtCoFe nanowires, respectively, produce better power conversion efficiency (PCE) of 8.10% for Pt33Co24Fe43 nanowire, 8.33% for Pt74Co12Fe14 nanowire, and 9.26% for Pt49Co23Fe28 nanowire in comparison to the PCE of Pt CE (7.32%). Further, the PRT‐22 DSSC with Pt49Co23Fe28 nanowire exhibits a maximum PCE of 12.29% with a certificated value of 12.0%, which surpass the previous PCE record of the DSSCs with Ru(II)‐based dyes. The photovoltaic and electrochemical results reveal the composition‐dependent activity along with a volcano‐shaped trend in the I?/ redox reaction. Theoretical work on the adsorption energies of I2, the desorption energies of I?, and the corresponding absolute energy demonstrates that the reduction activity followed in the order of Pt49Co23Fe28(111) plane > Pt74Co12Fe14(111) plane > Pt33Co24Fe43(111) plane, proving Pt49Co23Fe28 nanowire to be a superior cathode material for DSSCs. 相似文献
993.
Drug Carriers: Stimuli‐Responsive Nucleic Acid‐Based Polyacrylamide Hydrogel‐Coated Metal–Organic Framework Nanoparticles for Controlled Drug Release (Adv. Funct. Mater. 8/2018)
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994.
Discrete Event Dynamic Systems - This paper studies the scheduling problem for the manufacturing systems with uncertain job duration, and the possibility of planning due-date quotations for... 相似文献
995.
Drug Delivery: The Application of Stimuli‐Responsive VEGF‐ and ATP‐Aptamer‐Based Microcapsules for the Controlled Release of an Anticancer Drug,and the Selective Targeted Cytotoxicity toward Cancer Cells (Adv. Funct. Mater. 24/2016)
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996.
997.
Arafat A. A. Shabaneh Azizi Mohd Ali Chee Kyun Ng Nor Kamariah Noordin Aduwati Sali Mohd. Hanif Yaacob 《Wireless Personal Communications》2014,77(1):589-604
Energy conservation is one of the crucial issues in wireless sensor network (WSN). A significant solution to conserve energy is done by deploying duty cycle management mechanisms in the WSN applications. This paper reviews several duty cycle mechanisms in WSN such as Duty Cycle Learning Algorithm, adaptive media access control (MAC) protocol for efficient IEEE 802.15.4 (AMPE), distributed duty cycle management (DDCM), distributed duty cycle management low power broadcast (DDCM + LPB) and distributed beacon only period. These mechanisms change their parameters such as idle listening, packet accumulation and delay in the end device transmitting queue to improve the energy conservation in WSN. The performances of these different energy conservation mechanisms have been compared at the MAC layer of IEEE 802.15.4 standard. It is found that the DDCM + LPB has made approximately 100 % enhancement in terms of average energy efficiency as compared to the other mechanisms. DDCM + LPB has significant enhancements by adapting the duty cycle according to the network traffic load condition. Using this mechanism, the duty cycle is increased when the traffic load increases and vice versa. Its energy efficiency also outperforms the conventional DDCM by the average of 10 %. 相似文献
998.
Xian Huang Yuhao Liu Kaile Chen Woo‐Jung Shin Ching‐Jui Lu Gil‐Woo Kong Dwipayan Patnaik Sang‐Heon Lee Jonathan Fajardo Cortes John A. Rogers 《Small (Weinheim an der Bergstrasse, Germany)》2014,10(15):3083-3090
This paper introduces materials and architectures for ultrathin, stretchable wireless sensors that mount on functional elastomeric substrates for epidermal analysis of biofluids. Measurement of the volume and chemical properties of sweat via dielectric detection and colorimetry demonstrates some capabilities. Here, inductively coupled sensors consisting of LC resonators with capacitive electrodes show systematic responses to sweat collected in microporous substrates. Interrogation occurs through external coils placed in physical proximity to the devices. The substrates allow spontaneous sweat collection through capillary forces, without the need for complex microfluidic handling systems. Furthermore, colorimetric measurement modes are possible in the same system by introducing indicator compounds into the depths of the substrates, for sensing specific components (OH?, H+, Cu+, and Fe2+) in the sweat. The complete devices offer Young's moduli that are similar to skin, thus allowing highly effective and reliable skin integration without external fixtures. Experimental results demonstrate volumetric measurement of sweat with an accuracy of 0.06 μL/mm2 with good stability and low drift. Colorimetric responses to pH and concentrations of various ions provide capabilities relevant to analysis of sweat. Similar materials and device designs can be used in monitoring other body fluids. 相似文献
999.
基于散粒体宏-微观力学分析,首先提出了3类张量的概念,推导了散粒体三维应力-组构关系,接着给出了二维和轴对称条件下的应力-组构解析表达式,并采用双轴和三轴离散元(DEM)模拟结果对解析解进行了验证分析。最后基于应力-组构解析,采用“真应力”的概念分析了散粒体的强度问题。研究结果表明:散粒体中的应力分布受3类张量的共同影响,双轴与三轴的离散元模拟与解析关系较吻合。在略去了高阶项后,二维应力-组构关系式与Rothenburg等提出的表达式一致。进一步的分析表明:散粒材料强度受控于“真应力”,表观活动摩擦角的变化实质是颗粒摩擦和各向异性组构共同作用的结果。研究成果可以用于分析散粒体各向异性强度特征和本构关系。 相似文献
1000.